Now we know what really happened in the Shatt al-Arab waterway on March 23 and in the 13 days of captivity that followed for 15 British sailors and marines. It wasn't the lies you heard from Iran's top officials, starting with President Mahmoud Ahmadinejad, or the cruelly coerced statements of the British captives in Iran's propaganda videos.

The 15 Royal Navy sailors and Royal Marines were finally free to talk Friday, and they did, volubly.

Safely back in Britain, they flatly refuted the fairy tales told by the Iranians and the collaborating statements they had been pressured to make by their captors.

Were they, in fact, in Iraqi, not Iranian, territorial waters when they were seized in an obviously preplanned ambush by maritime units of Iran's heavily armed Revolutionary Guards?

Three sets of Global Positioning Satellite coordinates say they were right where the British government insisted they were - 1.7 miles inside the internationally recognized Iraqi side of the Shatt al-Arab waterway's boundary line. Their own hand-held GPS devices, those in a Royal Navy helicopter monitoring their movements from overhead and the precise navigational instrumentation of the British navy frigate Cornwall from which they operated all attested to their correct position.

In Iranian custody, several of the British service members made videotaped statements professing guilt for having "intruded" into Iranian waters. Multiple letters allegedly written by Faye Turney, the one female British sailor captured, stated that the Brits had "obviously" trespassed into Iranian waters. The letters, composed in stilted English, were clearly concocted by the Iranians, not written by Turney. Over the 13 days, the Iranians announced that all 15 of the British sailors and marines had "confessed" to being on Iran's side of the Shatt al-Arab.

Hogwash would be the polite term for Iran's claims and for these purported confessions.

How did the Iranians extract these admissions?

Not by the supposedly humane treatment they claimed to have accorded the captured young Britons. Quite the contrary.

In interviews Friday with reporters at a military base in England, the sailors and marines said they were subjected to unrelenting psychological pressure. For starters, their Iranian captors told them that if they confessed to violating Iran's sovereignty and territorial waters they would be freed in a matter of days. If they refused to confess, they would be put on trial, convicted and then spend up to seven years in prison in Iran. What would you do?

The former captives said they were kept in isolation. They knew nothing about what their own government, Britain's allies, the United Nations or anyone else was doing to free them. Seven years in an Iranian prison versus a transparent falsehood that they could disavow the moment they were released. They did what most of us would have done. They lent themselves as propaganda props to Iran's international deception.

Remember the seemingly reassuring video of the captives sitting together and eating from paper plates piled high with food? All agitprop, to borrow a Cold War term for propaganda and psychological warfare.

In reality, the freed captives now reveal, they were initially blindfolded, stripped of their uniforms, bound, pushed against a wall from which they could hear guns being cocked in the next room, and later confined in tiny individual cells. Isolation and solitary confinement are classic techniques for breaking the morale, group solidarity and resolution of prisoners.

These are techniques the Iranians, veteran hostage-takers, know well.

During the 444 days in which American diplomats and U.S. Embassy staff were held hostage in Iran from 1979 to 1981, the Iranians used death threats, repeated mock executions, selective beatings, coercive interrogations and all manner of psychological pressure to break their captives. In Lebanon during the 1980s, the Iranians orchestrated the kidnapping and holding for ransom of various Americans, mostly civilians, and others. The victims of this cruel torment were held for years, bound, isolated and constantly terrorized.

A CIA officer kidnapped in Lebanon was beaten and tortured to death. A kidnapped U.S. Marine major, assigned as liaison to United Nations peacekeepers in Lebanon, was shown in a grisly video hanged by his captors.

The Iranians were less physically brutal with their British captives but the coercive intent was the same: the cruel manipulation of hostages for Iran's international agenda of deception and intimidation.

British Prime Minister Tony Blair insists that no concessions were made and no deals, private or otherwise, struck with the Iranians to obtain the release of the 15 British sailors and marines. Let's hope so. Hostage-taking must never, ever be rewarded.

If Britain's government, its 15 Royal Navy sailors and Royal Marines and all the documentary navigational and GPS coordinates evidence the British have is correct, the armed seizure of these British military personnel was an act of piracy and war.

Britain's anti-smuggling, anti-terrorist enforcement mission in the Shatt al-Arab waterway is explicitly sanctioned by the United Nations. U.S. and Iraqi forces are performing the same mission in accordance with the same U.N. authorization. All, we must now conclude, are potentially vulnerable to Iranian attack along that narrow waterway or in the Persian Gulf.

Part of the appropriate deterrent is what military professionals would call more robust Rules of Engagement. In plain English, any future attempts at hostage-taking by Iran outside its territorial waters should be repelled by coalition forces fully authorized to defend themselves with lethal force.

Robert J. Caldwell is editor of The San Diego Union-Tribune's Sunday Insight section and can be reached via e-mail at robert.caldwell@uniontrib.com.